Power distribution apparatus

ABSTRACT

A power distributing apparatus is provided to reduce the number of voltage converters. The power distributing apparatus  1  includes a power source part  4  for supplying a power of 42V, an electrical connection box  7  connected with the part  4  through a power line  5,  and a plurality of electronic control units  8   a   , 8   b    . . . , 8   n . The electrical connection box  7  has a regular-supply converter  9  to convert a high voltage of 42V to an intermediate voltage higher than a load voltage of 5V. The regular-supply converter  9  can exhibit a high conversion efficiency when the apparatus is operated under high load. Each of the electronic control units  8   a   , 8   b    . . . , 8   n  has a series regulator  14  to convert the intermediate voltage to the load voltage. Owing to the supply of voltage higher than the load voltage by the regular-supply converter  9,  there is no need to consider inconvenience due to voltage drop between the converter and a remote load.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a power distribution apparatusmounted on a vehicle (or the like) to distribute an electrical power toa variety of electrical loads in the vehicle.

[0003] 2. Description of Related Art

[0004] In the conventional vehicle adopting a power source part of 14V(voltage), the power distribution apparatus includes an electricalconnection box to which high-voltage power is supplied from the powersource part, and a plurality of electronic control units connected tothe electrical connection box through power lines, the electroniccontrol units each having a built-in series regulator to which thehigh-voltage power is distributed. In operation, the high-voltage powerfrom the electrical connection box is converted into a low-voltage powerby the series regulators in the electronic control units. Then, theso-converted, low-voltage is supplied to a plurality of electrical loadsconnected to respective electronic control units.

[0005] Meanwhile, recently, there has been developed a “high-voltage”vehicle using a voltage of 42V, which is loaded with a motor generatoreffective to reduction in fuel consumption. However, if theabove-mentioned power distribution apparatus is applied to such ahigh-voltage vehicle, then the power distribution apparatus exhibits aremarkably-deteriorated conversion efficiency and also a great heatgeneration. That is, if the vehicle adopts a power source of 14V andfurther a voltage for each load is equal to 5V, then the seriesregulators each has an efficiency of 35.7% [=(14−5)/14]. While, if thevehicle adopts a power source of 42V and further a voltage for each loadis equal to 5V, the series regulator will have an efficiency of 11.9%[=(42−5)/42].

[0006] Hereat, although there might be supposed a method of adopting aswitching regulator in place of the series regulator, it is impossibleto prevent a battery from going flat. Because the switching regulatorhas a deteriorated conversion efficiency when the apparatus is operatedunder light load. In order to solve this problem, there has beenproposed a system where all electronic control units that requirestand-by currents (e.g. keyless unit) are respectively equipped withstand-by current suppliers. In this system, when an ignition switch isturned on, the power supply is accomplished by the switching regulators.On the other hand, when the ignition switch is turned off, the powersupply is accomplished by the stand-by current suppliers. However, sincethis system requires to arranged the expensive switching regulators forthe respective electronic control units and also requires to arrange thestand-by current suppliers for all of the electronic control units thatrequire stand-by currents, the manufacturing cost for the same system iselevated excessively.

[0007] In connection, Japanese Patent Application Laid-open No. 10-84626discloses another conventional power distributing apparatus where theelectrical connection box is supplied with high-voltage power from thepower source and also provided with a voltage converter which converts ahigh voltage into a low voltage (5V), so that the resultant low-voltagepower is supplied to respective electronic control units. Owing to theprovision of a single voltage converter, it is possible to construct thepower distributing apparatus at low cost.

[0008] In this power distributing apparatus, however, there arises aproblem of voltage drop in case of the power supply against electricalloads far from the voltage converter. In order to prevent such a farawaypower supply, it is necessary to increase the number of voltageconverters, causing the manufacturing cost to be elevated.

[0009] In addition, the voltage converter is required to meetrequirements of the most severe electrical load in terms of convertedvoltage and temperature characteristics, causing the production cost ofthe apparatus to be elevated. Since the converter is apt to output withpower fluctuations due to gain and loss in load currents, it isdifficult to supply the plurality of loads with accurate powers.

SUMMARY OF THE INVENTION

[0010] Under the circumstances, it is therefore an object of the presentinvention to provide a power distributing apparatus by which it ispossible to reduce the number of voltage converters to the utmost andwhich employs low-priced series regulators against which severe outputaccuracy are not required, whereby the apparatus can be constructed atlow price. Further, it is an object of the present invention to providea power distributing apparatus which has an improved efficiency toconvert a voltage of a power source and which is not accompanied withgreat heat-generation, allowing fuel consumption of vehicle to bereduced.

[0011] The object of the present invention described above can beaccomplished by a power distributing apparatus comprising:

[0012] a power source part for supplying power of a high voltage;

[0013] an upstream-side power distributing part connected with the powersource part through a power line thereby to accept power supply of thehigh voltage from the power source part;

[0014] a plurality of downstream-side power distributing parts connectedwith the upstream-side power distributing part through power linesthereby to accept power supply from the upstream-side power distributingpart and supply power of a load voltage to a plurality of loads;

[0015] a regular-supply converter disposed in the upstream-side powerdistributing part to convert the high voltage to an intermediate voltagelower than the high voltage and higher than the load voltage, theregular-supply converter capable of converting a voltage with a highconversion efficiency when the power distributing apparatus is operatedunder high load; and

[0016] a plurality of series regulators respectively disposed in thedownstream-side power distributing parts to convert the intermediatevoltage to the load voltage.

[0017] In the above power distributing apparatus, since theregular-supply converter supplies the downstream-side power distributingparts with the power of a voltage higher than the load voltage, there isno need to consider inconvenience due to voltage drop. Therefore, it ispossible to minimize the number of regular-supply converters.

[0018] Further, since the series regulators supply accurate load voltageto the respective loads, the regular-supply converter is not required tohave severe output accuracy. Since the downstream-side powerdistributing parts are respectively provided with the series regulators,they each has only to be equipped with temperature characteristics andaccuracy required for a load in charge of the correspondingdownstream-side power distributing part. Additionally, theregular-supply converter in the upstream-side power distributing part isconstructed to have an improved conversion efficiency. In operation, therespective series regulators convert the intermediate voltage as aresult of conversion by the regular-supply converter, into the loadvoltage.

[0019] As the second aspect of the invention, the above powerdistributing apparatus further comprises a standby-current supplyconverter disposed in the upstream-side power distributing part toconvert the high voltage to the intermediate voltage, the stand-bycurrent supply converter capable of converting a voltage with a highconversion efficiency when the power distributing apparatus is operatedunder light load; wherein both of the regular-supply converter and thestand-by current supply converter supply a stand-by current to thedownstream-side power distributing parts.

[0020] According to the second aspect of the invention, it is possibleto supply the stand-by current in a lump by the stand-by current supplyconverter having a high conversion efficiency when the apparatus isoperated under light load.

[0021] As the second aspect of the invention, the power distributingapparatus of the second aspect further comprises a current sensor fordetecting a current flowing from the upstream-side power distributingpart to the downstream-side power distributing parts and a controllerfor controlling the operations of the regular-supply converter and thestand-by current supply converter. Under condition that the powerdistributing apparatus is mounted on a vehicle having an ignitionswitch, the controller operates so as to activate the regular-supplyconverter thereby to carry out power supply to the downstream-side powerdistributing parts when the ignition switch is turned on; activate theregular-supply converter hereby to carry out the power supply when theignition switch is turned off and a current value detected by thecurrent sensor is more than a predetermined value; and activate thestand-by converter thereby to carry out the power supply when theignition switch is turned off and a current value detected by thecurrent sensor is less than the predetermined value.

[0022] According to the third aspect of the invention, when the ignitionswitch is turned off, it is executed to switch the operations of theregular-supply converter and the stand-by current supply converter on abasis of a current value detected by the current sensor. Thus, it ispossible to control the operation of the converters on a basis of actualcurrent values.

[0023] As the fourth aspect of the invention, the intermediate voltageis somewhat higher than the load voltage.

[0024] According to the fourth aspect of the invention, the powerdistributing apparatus converts the power of high voltage to a voltageclose to the load voltage by the regular-supply converter capable ofconverting a voltage with a high conversion efficiency when theapparatus is operated under high load.

[0025] As the fifth aspect of the invention, the downstream-side powerdistributing parts are electronic control units.

[0026] As the sixth aspect of the invention, the intermediate voltage isa voltage of power for driving the electronic control units.

[0027] According to the fifth and sixth aspects of the invention, it ispossible to divert the general-use electronic control units as thedownstream-side power distributing apparatus.

[0028] These and other objects and features of the present inventionwill become more fully apparent from the following description andappended claims taken in conjunction with the accompany drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029]FIG. 1 is a circuit block diagram of a power distributingapparatus in accordance with the first embodiment of the presentinvention;

[0030]FIG. 2 is a detailed circuit diagram of a part inside anelectrical connecting box, which is related to the power distributingapparatus, showing the first embodiment of the invention;

[0031]FIG. 3 is a wave diagram of respective outputs for explanation ofswitching respective outputs of a regular-supply converter and astand-by current supply converter, showing the first embodiment of theinvention;

[0032]FIG. 4 is a characteristic diagram of conversion efficiencyagainst load current, showing the first embodiment of the invention; and

[0033]FIG. 5 is a circuit block diagram of the power distributingapparatus in accordance with the second embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0034] Embodiments of the present invention will be described withreference to the drawings.

[0035] FIGS. 1 to 4 show the first embodiment of the present invention.In the first embodiment, there is presented an example where a powerdistributing apparatus 1 of the invention is mounted on a so-called“high-voltage” vehicle powered by 42V. In these figures, FIG. 1 is acircuit block diagram of the power distributing apparatus 1, while FIG.2 is a detailed circuit block diagram of a part inside an electricalconnecting box 7, which is related to the power distributing apparatus1. FIG. 3 is a wave diagram of respective outputs for explanation ofswitching respective outputs of a regular-supply converter 9 and astand-by current supply converter 10. FIG. 4 is a characteristic diagramof conversion efficiency against load current.

[0036] As shown in FIG. 1, the power distributing apparatus 1 includes apower source part 4 formed by a chargeable/dischargeable battery 2 and amotor generator 3 that can generate power owing to the revolutions of anengine. Through respective power lines 5, the power source part 4supplies three blocks 6 a, 6 b, 6 c with high-voltage power of 42Vrespectively. For example, these blocks 6 a, 6 b, 6 c corresponds to anengine room, a passenger's cabin and a trunk room, respectively. In eachof the blocks 6 a, 6 b, 6 c, there are provided an electrical connectionbox 7 as an upstream-side power distributing part and a plurality ofelectronic control units 8 a, 8 b . . . , 8 n as downstream-side powerdistributing parts. The electrical connection box 7 has a built-inregular-supply converter 9 and a built-in stand-by current supplyconverter 10. The “high-voltage” power of 42V is led to both of theregular-supply converter 9 and the stand-by current supply converter 10.

[0037] The regular-supply converter 9 is formed by a DC(directcurrent)/DC converter that can exhibit a high conversion efficiency whenthe apparatus 1 is driven under high load. The converter 9 converts ahigh-voltage of 42V into an intermediate-voltage power of 7V which issomewhat higher than a load voltage (5V). The output of theregular-supply converter 9 is supplied to all of the electronic controlunits 8 a, 8 b . . . , 8 n in the blocks 6 a, 6 b, 6 c through powerlines 11. The stand-by current supply converter 10 is formed by aDC(direct current)/DC converter that can exhibit a high conversionefficiency when the apparatus 1 is driven under light load.

[0038] The converter 10 converts a high-voltage of 42V into anintermediate-voltage power of 7V which is somewhat higher than a loadvoltage (5V), too. The output of the stand-by current supply converter 9is supplied to an electronic control unit which takes charge of anelectrical load (not shown) requiring a power even when an ignitionswitch (not shown) of the vehicle is turned off. For example, the outputof the stand-by current supply converter 9 is supplied to the electroniccontrol unit 8 a for supplying a stand-by current, through the powerline 11.

[0039] As shown in FIG. 2, the electrical connection box 7 contains acontroller 12 by which the operations of the regular-supply converter 9and the stand-by current supply converter 10 are controlledrespectively. The controller 12 does control the converters 9, 10 on theground of both ON/OFF state of the ignition switch and outputs from acurrent sensor 13. The details of contents controlled by the controller12 will be described later. The current sensor 13 detects a current ofthe power line 11 provided for both of the regular-supply converter 9and the stand-by current supply converter 10.

[0040] Back to FIG. 1 again, a plurality of electrical loads (not shown)are connected with the electronic control units 8 a . . . , 8 n forcontrolling the above loads. The electronic control units 8 a, 8 b, . .. 8 n have built-in series regulators 14 respectively, to which theintermediate voltage of 7V of the electrical connection box 7 is led.Each of the series regulators 14 is formed with a known structure thatstabilizes an output voltage by feedback of the changes of load voltageby means of e.g. operational amplifier, converting the intermediatevoltage of 7V into the load voltage of 5V. The output from each seriesregulator 14 is supplied to a plurality of electrical loads in charge ofthe corresponding regulator 14.

[0041] Referring to FIG. 3, the operation of the above-mentioned powerdistributing apparatus 1 will be described as follows. When the ignitionswitch is turned on, the regular-supply converter 9 is driven to converta high voltage of 42V to an intermediate voltage of 7V. The convertedintermediate voltage 7V is supplied to the electronic control units 8 a. . . , 8 n and then, the series regulators 14 in the units 8 a . . . ,8 n convert the intermediate voltage of 7V to the load voltage of 5V forthe respective electrical loads.

[0042] When the ignition switch is changed from its ON state to the OFFstate, the load current is reduced gradually. When the load currentbecomes less than a threshold value (a predetermined value), theoperation of the regular-supply converter 9 is stopped andsimultaneously, the drive of the stand-by current supply converter 10 isstarted. Consequently, the power supply for the electronic control units8 a, 8 b, . . . 8 n is altered from the regular-supply converter 9 tothe stand-by current supply converter 10.

[0043] Under condition that the ignition switch is turned off, if a loadcurrent becomes more than the threshold value due to the drive of anelectric load (e.g. drive of powered seat device), the operation of thestand-by current supply converter 10 is stopped and simultaneously, thedrive of the regular-supply converter 9 is started. That is, the powersupply for the electronic control unit 8 b is altered from theregular-supply converter 9 to the stand-by current supply converter 10.Then, when the so-elevated load current falls less than the thresholdvalue, the operation of the regular-supply converter 9 is stopped, whilethe drive of the stand-by current supply converter 10 is started again.

[0044] When the ignition switch is changed from the OFF state to the ONstate, the drive of the stand-by current supply converter 10 is stoppedirrespective of values of current detected by the current sensor 13,while the drive of the regular-supply converter 9 is started. That is,the power supply for the electronic control units 8 a, . . . , 8 n isaltered from the stand-by current supply converter 10 to theregular-supply converter 9.

[0045] According to the power distributing apparatus 1, since theregular-supply converter 9 supplies the electronic control units 8 a, 8b, . . . 8 n with a voltage (7V) higher than the load voltage (5V),there is no need to consider inconvenience of voltage drop between theunit(s) 8 a, 8 b, . . . 8 n and a remote electrical load(s). Therefore,it is possible to provide the apparatus 1 with the smallest number ofconverters 9. Further, in the electrical connection box 7, theregular-supply converter 9 is not required to have a severe outputaccuracy since the series regulators 14 supply accurate load voltage tothe respective electrical loads. Thus, it is possible to miniaturize aripple-absorption condenser etc. Since the electronic control units 8 a,. . . , 8 n are respectively provided with the series regulators 14,they each has only to be equipped with temperature characteristics andaccuracy required for the load in charge of the corresponding electroniccontrol unit. In addition to the above-mentioned reasons, by using noexpensive switching regulator but the series regulator, it is possibleto construct the power distributing apparatus 1 at low cost.Additionally, according to the invention, the regular-supply converter 9in the electrical connection box 7 is formed with structure of highconversion efficiency and the respective series regulators 14 convertthe intermediate voltage, which has been obtained by the regular-supplyconverter 9, into the load voltage. Thus, as shown in FIG. 4, it ispossible to reduce a loss in the voltage conversion efficiency and alsoheat generation, so that the fuel consumption of the vehicle can beimproved.

[0046] Further, since the accurate load voltage produced by the seriesregulators 14 is supplied to the respective loads, there is no need toshield the power lines 11 extending from the regular-supply converter 9to the series regulator 14.

[0047] According to the first embodiment of the invention, theelectrical connection box 7 is provided with the stand-by current supplyconverter 10 which has a high conversion efficiency at light load andconverts the power of high voltage of the power source part 4 into theintermediate voltage and further, both of the stand-by current supplyconverter 10 and the regular-supply converter 9 supply an electricalpower to the electronic control unit 8 b performing the power supply ofstand-by current. That is, since the stand-by current can be supplied ina lump by the stand-by current supply converter 10 that exhibits a highconversion efficiency when the apparatus is operated under light load,it is possible to restrict an occurrence of dark current to the utmost,so that the battery can be prevented from going flat.

[0048] According to the first embodiment of the invention, on theprovision of the current sensor 13 for detecting a current flowing fromthe electrical connection box 7 to the respective electronic controlunits 8 a, . . . , 8 n, when the ignition switch is turned on, it iscarried out to activate the regular-supply converter 9 for power supply.When the ignition switch is turned off and a current value detected bythe current sensor 13 is more than the predetermined value, it iscarried out to activate the regular-supply converter 9 for power supply.Further, when the ignition switch is turned off and a current valuedetected by the current sensor 13 is less than the predetermined value,it is carried out to stop the operation of the regular-supply converter9 and activate the stand-by converter 10 only. In this way, theoperations of both converters 9, 10 can be switched on a basis of anactual current value. Note, in the modification, the stand-by currentsupply converter 10 may be always activated irrespective of the ON/OFFstate of the ignition switch and also magnitude of a load current.

[0049] In the first embodiment, since the intermediate voltage has avalue of 7V somewhat larger than the load voltage (5V), the high voltageis converted to a voltage close to the load voltage by theregular-supply converter 9 exhibiting a high conversion efficiency whenthe apparatus is operated under high load. Thus, it is possible toreduce the loss of voltage-converting efficiency of the apparatus as awhole and the heat-generation furthermore, improving the fuelconsumption. Moreover, since the voltage drop through each seriesregulator 14 is small (2V=7−5), the heat generation is restrictedremarkably, so that it is possible to miniaturize the series regulators14. Note, although the intermediate voltage may be either 6V or anyvalue from 8V to 11V alternatively, it is necessary to establish avoltage value so as not to cause inconvenience due to the voltage dropat the remote series regulator 14.

[0050]FIG. 5 is a circuit block diagram plan view of a powerdistributing apparatus 20 in accordance with the second embodiment ofthe invention. As obvious from FIG. 5, the power distributing apparatus20 of this embodiment differs from the same apparatus 1 of the firstembodiment in that a regular-supply converter 21 and a stand-by currentsupply converter 22 convert a high voltage of 42V to an intermediatevoltage of 12V, which is equal to a voltage to drive electronic controlunits 23 a, . . . , 23 n, while respective series regulators 24 in theelectronic control units 23 a, . . . , 23 n convert the intermediatevoltage of 12V to the load voltage of 5V. Since the other constitutionsof this embodiment are similar to those of the first embodiment, theiroverlapping descriptions are eliminated. Also in FIG. 5, elementsidentical to those of the first embodiment are indicated with the samereference numerals respectively, for their clearness.

[0051] Both effects and operations of the apparatus of this embodimentare similar to those of the first embodiment.

[0052] Furthermore, since the intermediate voltage of the secondembodiment is established to be equal to drive voltage (12V) for theelectronic control units 24 as the downstream-side power distributingparts, it is possible to divert the general-use electronic control unitsas the downstream-side power distributing parts, whereby the powerdistributing apparatus 20 can be manufactured at low price.

[0053] Again, it will be understood by those skilled in the art that theforegoing descriptions are nothing but one embodiment of the disclosedpower distributing apparatus and the modifications. In addition to theabove modifications, various changes and modifications may be made tothe present invention without departing from the spirit and scope of theinvention.

What is claimed is:
 1. A power distributing apparatus comprising: apower source part for supplying power of a high voltage; anupstream-side power distributing part connected with the power sourcepart through a power line thereby to accept power supply of the highvoltage from the power source part; a plurality of downstream-side powerdistributing parts connected with the upstream-side power distributingpart through power lines thereby to accept power supply from theupstream-side power distributing part and supply power of a load voltageto a plurality of loads; a regular-supply converter disposed in theupstream-side power distributing part to convert the high voltage to anintermediate voltage lower than the high voltage and higher than theload voltage, the regular-supply converter capable of converting avoltage with a high conversion efficiency when the power distributingapparatus is operated under high load; and a plurality of seriesregulators respectively disposed in the downstream-side powerdistributing parts to convert the intermediate voltage to the loadvoltage.
 2. The power distributing apparatus as claimed in claim 1,further comprising a standby-current supply converter disposed in theupstream-side power distributing part to convert the high voltage to theintermediate voltage, the stand-by current supply converter capable ofconverting a voltage with a high conversion efficiency when the powerdistributing apparatus is operated under light load; wherein both of theregular-supply converter and the stand-by current supply convertersupply a stand-by current to the downstream-side power distributingparts.
 3. The power distributing apparatus as claimed in claim 2,further comprising a current sensor for detecting a current flowing fromthe upstream-side power distributing part to the downstream-side powerdistributing parts and a controller for controlling the operations ofthe regular-supply converter and the stand-by current supply converter;wherein, under condition that the power distributing apparatus ismounted on a vehicle having an ignition switch, the controller operatesso as to: activate the regular-supply converter thereby to carry outpower supply to the downstream-side power distributing parts when theignition switch is turned on; activate the regular-supply converterthereby to carry out the power supply when the ignition switch is turnedoff and a current value detected by the current sensor is more than apredetermined value; and activate the stand-by converter thereby tocarry out the power supply when the ignition switch is turned off and acurrent value detected by the current sensor is less than thepredetermined value.
 4. The power distributing apparatus as claimed inclaim 1, wherein the intermediate voltage is somewhat higher than theload voltage.
 5. The power distributing apparatus as claimed in claim 1,wherein the downstream-side power distributing parts are electroniccontrol units.
 6. The power distributing apparatus as claimed in claim5, wherein the intermediate voltage is a voltage of power for drivingthe electronic control units.